Various types of wireless systems that utilize channels in frequency spectrum shared with other systems have been proposed. The sharing of frequency spectrum allows a wireless system to increase system bandwidth when channels in the shared frequency spectrum are available for use by the wireless system. In various systems, the shared frequency spectrum may be spectrum in unlicensed frequency bands or spectrum in licensed/allocated frequency bands that are shared between licensed systems, for example, on a prioritization basis. The prioritization may be implemented on a tier level basis, in which different levels of priority for use of the frequency spectrum are assigned to different systems.
An example of a system that utilizes spectrum in unlicensed frequency bands is a long term evolution unlicensed band (LTE-U) system. LTE-U is a technology that enables base stations to operate using LTE technology on shared channels in the 5 GHz and 3.5 GHz unlicensed bands that are primarily used for devices in Wi-Fi systems. Another example of a system utilizing shared frequency spectrum is a Dynamic Spectrum Access (DSA) system. A DSA system is typically configured so that base stations/systems within the DSA system use channels in a frequency spectrum shared with other base stations/systems of the DSA system under the coordination of a controller that manages a channel assignment database. Various groups in the wireless industry are currently working to standardize operating rules for DSA systems that have multiple levels of priority for spectrum access. A DSA system having multiple levels of priority is commonly known as a shared access system (SAS).